Unilateral dependant pulmonary edema during laparoscopic donor nephrectomy: report of three cases.

SUMMARY
Unilateral pulmonary edema of the dependant lung was observed in three patients during laparoscopic donor nephrectomy. Patients were treated with O2 supplementation by face mask, fluid restriction and diuretic. All the patients were relieved of symptoms with radiological improvement. The possible causes of this unusual complication following laparoscopic surgery appear to be prolonged lateral decubitus position and high intraoperative fluid infusion.


Introduction
Laparoscopic livedonor nephrectomyis currently an established method ofkidney procurement at many institutions worldwide. This offers less post-operative pain, shorter hospitalstay andearly post operative convalescence to the donor. [1][2][3] Despite these advantages, laparoscopic donor nephrectomy may beassociated witharrhythmias, pneumothorax and pneumomediastinum. 4,5 Recently, unilateral pulmonary edema is described for the first time during laparoscopic donor nephrectomy. 6 We report three cases of unilateral dependant pulmonary edema during laparoscopicdonor nephrectomy.Patients were treated with O2 supplementation, fluid restriction and diuretics.We report this complicationpossibly secondary to overhydration and prolonged lateral decubitus position in laparoscopic donor nephrectomy.

Case 1
A healthy 40-year-old 60kgman withASA-I was posted for laparoscopic donor nephrectomy.He was given balanced generalanaesthesia. Inductionwas with thiopentalsodium and suxamethonium was given to facilitate endotrachealintubation. Nitrousoxide, isoflurane and vecuronium were used for maintenance anaesthesia. Continuous monitoringwith ECG, SpO2, EtCO2, NIBP, airway pressure and urine output, temperature was performed.Patient wasgiven lateraldecubitus position for surgery and totaltime in this position was 5½ hours.The patient was hydrated with 7.5 L of fluids whichincluded 7Lof lactated Ringer's solution and 500 ml of gelofusine. 30g of 20% mannitol was given for osmotic diuresisbefore renalarterialdissectionand again 15 minutes prior to clamping of the renal artery. The total intraoperative urine output was 2L.
After kidney procurement, patient'ssaturation fell from 100% to 94%. On examination of chest, fine crepitations in dependant lungwere audible. The airway pressure was increased to 5 mm Hg from the baseline. Intravenous furosemide was given in dose of 40mgand fluid administrationwas stopped.X-ray chest revealed unilateraledema ofthe dependantlung (Fig.1). The SpO2 improved to 98% and an additional urine output of 1500ml obtained over 3 hours after diuretic. Patient was extubated after clinical and radiological improvement.

Case 2
A 55-year-old 65kg man with ASA-I was donor. Patient positioningand anaesthesia andmonitoringwere similar to thosein case I. Thetotaltimein the right lateral decubitus was6 hours. There wasdrop inO2 saturation from 100% to 93% gradually and increase in airway pressure at incision closure time. The patient was hydrated with 8Loffluidof balancedlactated Ringer's solution and Gelofusine.Mannitolwasgiven whilerenalarterial dissection and 15 minutes prior to renal artery clamp.Totalurineoutput was3150 ml.During auscultation ofchest, he had finecrepitations ondependant lung. X-ray chest was performedand diagnosis of unilateral pulmonary edema was confirmed. Patient was treated with O2with face mask, head up position, fluid restriction and diuretics; extubationwas performed in recovery room. In recovery room, urine output was 2415 ml.He was recovered on 1 st postoperative day.

Case 3
A58-year-old 45kg female, having history of hypertension was on single regular antihypertensive.She was subjected for laparoscopic donor nephrectomy. Patient positioningand anaesthesia were similar in to those in case-1 and 2.The total time in the lateral decubitus was 5 hours. She had drop in oxygen saturation at the time of kidney procurement. Total fluid was 5L which included lactated Ringer'ssolution and500ml of Gelofusine. Mannitol was given. Urine output was 2450ml.She had crepitation on dependant lungand O2 saturation remained between94%-95% tillthe completion of surgery. She was extubated and shifted to re-coveryroom. Treatment similar tocase -1,2were given In recovery room urine output was 3225 ml. She was alsorecovered infirst postoperative day with clear chest and clear chest radiograph.

Discussion
Prolonged pneumoperitoneum an d high intraabdominal pressure cause decreased renal blood flow, oliguria and renal dysfunction in the recipient as first demonstrated in a porcine model by London and colleagues. 7 The most probable explanation is that in addition to direct compression of the renalarteries by the pneumoperitoneum, the pressure exerted on the inferior vena cava results in partialcompression that increases venous resistance, thereby decreasing preload and stroke volume. To alleviate these effects, vigorous intravenous hydrationis recommendedin anattempt to optimize preload and promote diuresis. In a porcine model,Demyttenaere et alhave shown thatthe decrease in stroke volume and renalcortical perfusion could be prevented by simple hydration of 15ml.kg -1 .h -1 saline combined with a bolus 20 ml.kg -1 saline. 8 In addition, lateral decubitusposition contributes to hemodynamic alterations by decreasing preload throughthe effectofgravityon venousreturn.Yokoyama etalfoundno significantchange inhemodynamic values after posturalchange oftheir patientsfrom supine to lateral but a significant reduction in stroke volume after postural change to kidney position; these patients received a fluidregime of 20 ml.kg -1 .h -1 of crystalloids. 9 In accordance with the literature, we have hydrated all donors with 15 ml.kg -1 .hour -1 .Though most of our donors had no detrimental effect of aggressive fluid regime, three developed unilateral pulmonary edema. The possible explanation for development of unilateral pulmonary edema is overzealous hydration of the donor in lateraldecubitus position. The lateral decubitusposition altersthe physiology of pulmonary ventilation & perfusion. The dependant zones of the lung become hyperperfused & hypoventilated where as the non dependant portion become hypoperfused  10,11 Prolonged surgery was the only riskfactor found in all three cases.Morrisroe et al have recently shown unilateral pulmonary edema after laparoscopic donor nephrectomy in two cases. 6 The combination of patient factors, intraoperative hydration mandatory to ensureoptimalkidneyfunction duringlaparoscopic procurement, and prolonged decubituspositioning together were thought to bethe causeof dependantlung edema.
Routinely, we are not monitoringcentral venous pressure because central venous pressure monitoring will not help much in lateral position [12][13] . Preoperative hydration may improve renalhemodynamic as well as decrease the intraoperative fluid requirements. In a prospective randomized dose-finding study Martens Zur Borg etal have suggested that overnight infusion and a bolus of colloid just beforepneumoperitoneum attenuate hemodynamic compromise from pneumoperitoneum. 14 Though we have not practiced, such strategy may decrease intraoperativefluid requirement.
In conclusion, overzealous hydration during laparoscopic donor nephrectomy requiringmore than 5 hours time may lead to pulmonary edema of the dependant lung. Loopdiuretics and restriction of fluid infusion is required to treat such condition.